Fire authorities are concerned a change in the weather tomorrow could whip up the huge Gell River wilderness fire in Tasmania's southwest.
It's torn through more than 17,000 hectares of buttongrass and mixed forest along the Denison Range but no longer poses an immediate threat to property.
Sprinklers are being used to dampen down vulnerable wilderness areas.
A smoke alert also remains in place for the Derwent Valley and Greater Hobart regions.
Asthma Foundation of Tasmania's General Manager Wendy Evans advises those who are vulnerable to have an up-to-date plan or see their GP for a review.
“It can be life-threatening for people. They should stay indoors and keep their windows and doors closed, minimise the amount of outdoor physical activity. If they’ve got an air conditioner or heat pump at home or in the car they should set it to recycle,” she said.
The foundation also recommends those at risk to minimise their exposure to other irritants such as cigarette smoke and dust.
Advice is available from the Department of Health www.dhhs.tas.gov.au/publichealth/air/bushfire_smoke or the Asthma Foundation of Tasmania www.asthmatas.org.au